Repair Bond Strength of High-viscosity Glass-ionomer Cements Using Resin Composite Bonded with Light- and Self-cured Adhesive Systems.

CLINICAL RELEVANCE: High-viscosity glass-ionomer cements (HVGICs) used with atraumatic restorative treatment can be repaired with light- or self-cured adhesive systems; however, the repair bond strength of two-step, self-etching and one-step adhesives in the light-cure mode surpass one-step self-cure adhesives. Working on a feasible self-cure approach in the absence of such in rural areas as well as in war zones is of prime importance.

Microshear Bond Strength of High-viscosity Glass-ionomer to Normal and Caries-affected Dentin Under Simulated Intrapulpal Pressure.

OBJECTIVES:: The use of high-viscosity glass-ionomer cements (HVGICs) for atraumatic restorative treatment (ART) restorations is widely practiced with the advent of various HVGICs. However, the bonding of the latter to caries-affected dentin (CAD) should be validated, especially because it is the common substrate left after conservative caries removal following the ART approach. Hence, this study was carried out to evaluate the microshear bond strength (µSBS) of three HVGICs to normal dentin (ND) and CAD under intrapulpal pressure (IPP) simulation. METHODS AND MATERIALS:: The occlusal enamel of 90 molars with mid-coronal caries was cut to expose flat dentin surfaces containing both ND and CAD. Dentin substrates (ND and CAD) were differentiated using visual, tactile, caries-detecting dye, and dye-permeability methods. Prepared crown segments were equally divided (n=30) according to the tested HVGICs into GC Fuji IX GP Fast, Fuji IX GP containing chlorhexidine, and zinc-reinforced ChemFil Rock HVGIC. Microcylinders of tested HVGICs were built up on both dentin substrates (n=30 for each tested HVGIC per each substrate) using starch tubes while the specimens were subjected to simulated IPP of 15 mm Hg. The µSBS test was conducted using a universal testing machine, and failure modes were determined using a scanning electron microscope. Data were statistically analyzed using two-way analysis of variance (ANOVA) with repeated measures, one-way ANOVA, and Bonferroni post hoc tests (α=0.05). RESULTS:: For both dentin substrates (ND and CAD), the µSBS values of ChemFil Rock were significantly higher than those recorded for the other HVGICs. The µSBS values of each tested HVGIC to ND and CAD were not statistically different. Failure modes were mainly mixed. CONCLUSIONS:: Zinc-reinforced HVGIC ChemFil Rock showed superior bonding to ND and CAD compared to the GC Fuji IX GP Fast and Fuji IX with chlorhexidine. However, each of the tested HVGICs showed comparable bonding to both dentin substrates (ND and CAD).

Microshear Bond Strength of Adhesives to Enamel Remineralized Using Casein Phosphopeptide Agents.

OBJECTIVE: This study was carried out to evaluate the difference between bonding to demineralized enamel and remineralized enamel using casein phosphopeptide-amorphous calcium phosphate with fluoride (CPP-ACFP) or without fluoride (CPP-ACP) compared to normal enamel. Another aim was to test if the newly introduced Single Bond Universal adhesive system would show better bonding to any enamel condition in comparison to the other tested adhesive systems. METHODS: The lingual enamel surfaces of 40 non carious human third molars were divided into four main groups according to the enamel condition (ground normal enamel [negative control]; demineralized enamel [positive control]; and remineralized enamel with CPP-ACP or with CPP-ACFP, respectively). Within each main group, the lingual enamel surface of each tooth was sectioned into three slabs, resulting in 30 slabs that were distributed into three subgroups according to the adhesive system utilized (Clearfil S(3) Bond Plus, Single Bond Universal, or G-aenial Bond). Two resin composite microcylinder buildups were made on each enamel slab using Filtek Z350 XT. The µSBS was evaluated at a crosshead speed of 0.5 mm/min. Modes of failure were detected using an environmental scanning electron microscope at 300× magnification. RESULTS: The two-way analysis of variance with repeated measures revealed a significant effect for the enamel condition. However, there was no significant effect for the type of adhesive system. The interaction between the enamel condition and the type of adhesive system was also not significant. Modes of failure were mainly adhesive except for the demineralized enamel. It showed a mixed type of failure, in which cohesive failure in enamel was recorded. CONCLUSIONS: All single-step self-etch adhesives revealed comparable µSBS values to ground enamel and enamel remineralized with CPP-ACP or CPP-ACFP. Bonding to demineralized enamel was ineffective. With any enamel condition, no tested single-step self-etch adhesive was superior in its bonding.

One-year Adhesive Bond Durability to Coronal and Radicular Dentin Under Intrapulpal Pressure Simulation.

OBJECTIVE: To evaluate the microtensile bond strength (µTBS) of different adhesives to coronal vs radicular dentin after one year of storage in artificial saliva and under intrapulpal pressure (IPP) simulation. METHODS AND MATERIALS: Roots of 36 freshly extracted premolars were sectioned 5 mm apical to the cemento-enamel junction and pulp tissue was removed. Buccal enamel and cementum were trimmed to obtain standardized flat dentin surfaces. Specimens were divided into three groups (n=12/group) according to the adhesive strategies utilized: a two-step etch-and-rinse adhesive; a two-step self-etch adhesive; and a single-step self-etch adhesive. Adhesives and resin composite were applied to coronal and radicular dentin while the specimens were subjected to IPP simulation. After curing, specimens were stored in artificial saliva at 37°C in a specially constructed incubator while the IPP was maintained for either 24 hours or one year prior to testing. Bonded specimens were sectioned into sticks with a cross section of 0.8 ± 0.01 mm(2) and subjected to µTBS testing. Data were statistically analyzed using multi-way analysis of variance (ANOVA) with repeated measures; one-way ANOVA tests; and Bonferroni post hoc test (p<0.05). Failure modes were determined using a scanning electron microscope at 100× magnification. RESULTS: ANOVA results revealed a statistically significant effect for the adhesive strategy (p<0.001) and storage period (p<0.001) as well as for their interaction (p=0.024) on the µTBS. However, dentin substrate and its interactions revealed no significant effects. For both dentin substrates, the two-step self-etch adhesive revealed statistically significantly higher µTBS values than did the other two adhesives after 24 hours and one year of storage. After one-year storage, a significant decrease in bond strength values of all tested adhesives occurred with both dentin substrates. Modes of failure were mainly adhesive and mixed. CONCLUSIONS: Adhesives were not sensitive to structural differences between coronal and radicular dentin even after one year of storage under IPP simulation. However, all tested adhesive systems strategies were sensitive to storage.

Bond durability of different resin cements to caries-affected dentin under simulated intrapulpal pressure.

OBJECTIVE: To evaluate the durability of the bond of different resin cement systems to normal dentin (ND) and caries-affected dentin (CAD) with and without simulated intrapulpal pressure (IPP). METHODS AND MATERIALS: Molars with midcoronal caries were used. Occlusal enamel was cut to expose both dentin substrates (ND and CAD). Dentin substrates were differentiated using visual, tactile, caries-detecting dye, and dye-permeability methods. Prepared crown segments were equally divided according to the tested resin cement systems: etch-and-rinse resin cement, self-etch resin cement containing methacryloyloxydecyl dihydrogen phosphate (MDP), and self-adhesive resin cement. In addition to the dentin substrates and the resin cement types, the effect of application/storage conditions (with or without simulated IPP and with or without thermocycling) were tested. A microtensile bond strength test was done using a universal testing machine. Failure modes were determined using a scanning electron microscope. RESULTS: Etch-and-rinse resin cement strength values were significantly affected by the difference in the dentin substrates as well as the different application/storage conditions. Self-etch adhesive containing MDP bonded equally to ND and CAD and remained stable under all tested conditions. Self-adhesive resin cement revealed a similar bond to ND and CAD; however, its values were the lowest, especially when IPP and thermocycling were combined. Mixed failure was the predominant failure mode. CONCLUSIONS: Etch-and-rinse resin cement was sensitive to dentin substrate and application/storage conditions. Resin cement with self-etch adhesive containing MDP revealed more reliable bonding to ND/CAD even when IPP and thermocycling were combined. The bonding of the self-adhesive resin cement could not compete with other resin cements.

Reinforcement of teeth with simulated coronal fracture and immature weakened roots using resin composite cured by a modified layering technique.

OBJECTIVE: The purpose of this study was to evaluate the strengthening effect of resin composite, cured by a modified layering protocol, for teeth with simulated coronal fracture and weakened immature roots. METHODS: Fifty maxillary teeth were decoronated and their apices sectioned to standardize the length to 12 mm. Prepared teeth were equally distributed into five groups. Group 1VF root apices were flared with Pesso drills up to size 6. The roots were flared until a dentin thickness of only 1 ± 0.2 mm remained. Root ends were filled with mineral trioxide aggregate. The canals were backfilled with Vertise Flow following a modified layering protocol using two light-transmitting posts size 6 and 3. Next, a DT light post size 2 was cemented using the same material. Groups 2TS/MF and 3ED/PF were prepared and cured in the same way as group 1VF but filled with Clearfil Tri-S Bond/Majesty Flow and ED Primer II/Panavia F2.0 respectively. Group 4UF was similarly prepared but left unfilled (control). In group 5NW, roots were unflared but similarly filled as in group 3ED/PF. After 24 hours of storage, the fracture load was measured. The degree of cure for each tested material was indirectly measured using microhardness at different root levels (cervical, middle, and apical). Data were analyzed using one-way analysis of variance followed by Newman-Keuls post hoc test. RESULTS: Fracture load results revealed that groups 1VF and 2TS/MF had no statistically significant difference from group 5NW (p>0.05). For each tested material, no significant difference was found among microhardness values at different root levels. CONCLUSION: It may be possible to reinforce the teeth with coronal fracture and immature weakened roots to be comparable with unweakened ones when composite is applied and cured by the modified layering technique.

Bond durability of self-etch adhesive to ethanol-based chlorhexidine pretreated dentin after storage in artificial saliva and under intrapulpal pressure simulation.

OBJECTIVE: To evaluate the bond strength durability of a single-step self-etch adhesive to dentin pretreated with either ethanol-based chlorhexidine (ECHX) or water-based chlorhexidine (WCHX) after storage in artificial saliva and under intrapulpal pressure simulation (IPPS). METHODS: The occlusal enamel of 30 freshly extracted premolars was trimmed to expose midcoronal dentin. Roots were sectioned to expose the pulp chamber. Specimens were distributed over three groups (n=10) according to the dentin pretreatment used. In the first group, Adper Easy One (3M ESPE) was applied to the dentin surfaces according to the manufacturer's instructions (control group). In the second group, dentin was pretreated before bonding with 1 mL of 2% CHX diacetate dissolved in 100% ethanol (ECHX). The third group received the same pretreatment; however, CHX was dissolved in distilled water (WCHX). Pretreatment and bonding were carried out while the specimens were subjected to IPPS. Resin composite (Valux Plus, 3MESPE) buildups were made. After curing, specimens were stored in artificial saliva and under IPPS at 37°C in a specially constructed incubator (n=5/group) either for 24 hours or six months prior to testing. Thereafter, bonded specimens were sectioned into sticks with a cross section of 0.9 ± 0.01 mm(2) and subjected to microtensile bond strength (µTBS) testing (n=25/subgroup) using a universal testing machine. Data were statistically analyzed using two-way analysis of variance (ANOVA) with repeated measures, one-way ANOVA , and Bonferroni post hoc tests (p≤0.05). Failure modes were determined using a scanning electron microscope. RESULTS: After 24 hours of storage, control and WCHX groups revealed significantly higher µTBS than the ECHX group. After six-month storage in artificial saliva and IPPS, only the WCHX group maintained its µTBS value. The predominant mode of failure was the mixed type, except for the ECHX group, which was mostly adhesive. CONCLUSION: Pretreatment of the dentin with ECHX had a negative effect on bonding of the tested single-step self-etch adhesive; however, WCHX showed bond stability under IPPS.

Bond durability of adhesives containing modified-monomer with/without-fluoride after aging in artificial saliva and under intrapulpal pressure simulation.

OBJECTIVE: To evaluate the dentin bond strength durability of adhesives containing modified-monomer with/without-fluoride after storage in artificial saliva and under intrapulpal pressure simulation (IPPS). MATERIALS AND METHODS: The occlusal enamel of 48 freshly extracted teeth was trimmed to expose midcoronal dentin. Roots were sectioned to expose the pulp chamber and to connect the specimens to the pulpal-pressure assembly. Specimens were assigned into four groups (n=12) according to adhesive system utilized: a two-step etch-and-rinse adhesive system (SB, Adper Single Bond 2, 3M ESPE), a two-step self-etch adhesive system (CSE, Clearfil SE Bond, Kuraray Medical Inc), and two single-step self-etch adhesives with the same modified monomer (bis-acrylamide)-one with fluoride (AOF, AdheSE One F, Ivoclar-Vivadent) and the other without (AO, AdheSE One, Ivoclar-Vivadent). Bonding was carried out while the specimens were subjected to 15-mm Hg IPPS. Resin composite (Valux Plus, 3M ESPE) buildups were made. After curing, specimens were aged in artificial saliva and under 20-mm Hg IPPS at 37°C in a specially constructed incubator either for 24 hours or six months prior to testing. Bonded specimens (n=6/group) were sectioned into sticks (n=24/group) with a cross section of 0.9 ± 0.01 mm(2) and subjected to microtensile bond strength (µTBS) testing using a universal testing machine. Data were statistically analyzed using two-way analysis of variance (ANOVA) with repeated measures, one-way ANOVA tests, and a t-test (p<0.05). Failure modes were determined using a scanning electron microscope. RESULTS: The µTBS values of SB and CSE fell significantly after six-month storage in artificial saliva and under IPPS, yet these values remained significantly higher than those for the other two adhesives with modified monomers. There was no significant difference in the bond strength values between fluoride-containing and fluoride-free self-etch adhesive systems (AOF and AO) after 24 hours or six months. Modes of failure were mainly adhesive and mixed. CONCLUSIONS: Based on the results of this study, 1) Fluoride addition did not affect dentin bond durability; and 2) despite the fact that the single-step adhesive system with modified monomer showed stability, bond strengths associated with these systems remained lower than those of multistep adhesive systems.

Effect of using silorane-based resin composite for restoring conservative cavities on the changes in cuspal deflection.

OBJECTIVE: To investigate the effect of using two resin-composite materials for restoring conservative mesio-occluso-distal (MOD) cavities on the changes (incremental and cumulative) in cuspal deflection. METHODS: Forty extracted sound human maxillary second premolars were subjected to standardized MOD cavity preparation and then divided into two groups (n=20). The first group of teeth was restored with Filtek Z250 (3M ESPE, St Paul, MN, USA), and Filtek P90 (3M ESPE, St Paul, MN, USA) was used in the second group. Incremental cuspal deflection was calculated by measuring the intercuspal distance between the indexed cusp tips before the restoration and at five-minute intervals up to 30 minutes using a stereomicroscope connected to a digital camera. Cumulative cuspal deflection for both materials was also calculated. RESULTS: Comparing the incremental cuspal deflection of the tested groups at each time interval, it was found that there was no significant difference immediately after curing and at five, 15, 20, and 25 minutes. However, a significant difference was recorded at 10 and 30 minutes. For the cumulative cuspal deflection, Filtek P90 showed significantly lower deflection values than Filtek Z250 only after five minutes. CONCLUSIONS: Incremental cuspal deflections of both materials over the tested intervals were almost comparable. However, after five minutes of curing, silorane-based resin composite surpassed the methacrylate-based resin composite in controlling the cumulative cuspal deflection.

Long-term nanoleakage depth and pattern of cervical restorations bonded with different adhesives.

PURPOSE: This study investigated the effect of water storage on nanoleakage depth and the pattern of cervical cavities bonded with different adhesives. METHODS: For nanoleakage depth evaluation, standardized cervical cavities (2 mm in diameter) were prepared on the buccal and lingual surfaces of 36 intact human premolars. Specimens were divided into three groups (n=12) according to the three adhesive systems used: an etch-and-rinse adhesive (SBMP, Adper Scotchbond Multi-Purpose, 3M ESPE) and two single-step self-etch adhesives; one was mild and acetone based (IB-iBond, Kulzer), while the other was strong water based (PL, Adper Prompt L-Pop, 3M ESPE). All cavities were restored using Filtek Z250 (3M ESPE) resin composite. For each adhesive, specimens (n=12 with 24 restored cavities) were subdivided into three subgroups (n=4 with eight cavities) according to the storage period before examination (24 hours, three or six months). Another duplicate of teeth was prepared in the same way for nanoleakage pattern evaluation. After storage, the specimens were placed in 50%W/V silver nitrate solution for 24 hours and immersed in a photo-developing solution for eight hours. Thereafter, the specimens were sectioned buccolingually, polished, and examined by scanning electron microscopy. For nanoleakage pattern, specimens were treated in the same way as for nanoleakage depth except that they were additionally immersed in 10% EDTA for five seconds after polishing. Silver penetration percentage was calculated to the total length of the tooth-restoration interface. Data were analyzed with two-way analysis of variance, Kruskal-Wallis, and post hoc tests. RESULTS: After 24 hours, the least amount of nanoleakage depth was recorded for IB, while the highest was recorded for PL. For stored specimens, there was no significant difference among the nanoleakage depths of all adhesives. The tested adhesives recorded different nanoleakage patterns; however, there was an increase in the intensity and continuity of silver deposition by time. CONCLUSIONS: After 24 hours, the nanoleakage depth/pattern varied with the type of adhesive used; however, after water storage, all adhesives performed equally.

Caries experience of Egyptian adolescents: does the atraumatic restorative treatment approach offer a solution?

OBJECTIVES: To assess the prevalence and severity of dental caries amongst Egyptian adolescents and the prevalence of carious lesions treatable through the atraumatic restorative treatment (ART) approach. SUBJECTS AND METHODS: Using a convenient sample procedure, two secondary schools with a dental clinic were selected (967 students, average age: 13.7 ± 0.8 years, range: 12-15). Dental caries was diagnosed using the ART caries criteria, and plaque and calculus were assessed using the Green and Vermillion criteria amongst students grades 1-3 in the dental clinic by 3 calibrated examiners. The effect of the independent variables gender, age, tooth surface, jaw side (left or right) and type of jaw (mandible/maxilla) on dependent caries experience variables and D(2) and D(3) variables were tested using ANOVA. RESULTS: The prevalence of dental caries including enamel lesion (D(2)MFT) amongst the 967 students was 51.4% and that of dental caries excluding enamel lesions (D(3)MFT) was 38.1%. The mean D(2)MFT and D(3)MFT scores were 1.5 and 0.8, respectively. The percentage of teeth filled and extracted was low. Female students had statistically significantly higher mean D(3)MFT/S and D(2)MFT/S scores than males (p < 0.0001). The prevalence of cavitated carious lesions (D(3)) treatable through ART was 48% for score 2 and 28% for score 3. CONCLUSIONS: Most of the cavitated lesions were found untreated despite the presence of a dental clinic and a dentist on the school premises. The majority of cavitated lesions without pulp involvement could be treated using the preventive and restorative components of the ART approach.

Effect of chlorhexidine pretreatment on bond strength durability of caries-affected dentin over 2-year aging in artificial saliva and under simulated intrapulpal pressure.

OBJECTIVE: To evaluate the influence of 2% and 5% chlorhexidine (CHX) pretreatment on bond durability of a self-etching adhesive to normal (ND) and caries-affected (AD) dentin after 2-years of aging in artificial saliva and under simulated intrapulpal pressure (IPP). METHODS: One hundred twenty freshly extracted carious teeth were ground to expose ND and AD. Specimens were distributed into three equal groups (n=40) according to whether the dentin substrates were pretreated with 2% or 5% CHX or with water (control). Clearfil SE Bond (Kuraray) was applied to both substrates and composite cylinders (0.9 mm diameter and 0.7 mm height) were formed. Pretreatment and bonding were done while the specimens were subjected to 15 mm Hg IPP. After curing, specimens were aged in artificial saliva at 37°C and under IPP at 20 mm Hg until being tested after 24 hours or 2 years (n=20/group). Microshear bond strength was evaluated. Failure modes were determined using a scanning electron microscope (SEM) at 400× magnification. Data were statistically analyzed using three-way analysis of variance (ANOVA); one-way ANOVA tests, and t-test (p<0.05). Additional specimens (n=5/group) were prepared to evaluate interfacial silver precipitation. RESULTS: For the 24-hour groups, there were no significant differences among the ND groups and AD groups. For ND aged specimens, the 5% CHX group had the highest value followed by the 2% CHX and control groups, although the difference was statistically insignificant. For AD aged specimens, the 5% CHX group revealed statistically higher bond values compared to the 2% CHX and control groups. Fracture modes were predominately adhesive and mixed. Different interfacial silver depositions were recorded. CONCLUSIONS: Two percent or 5% CHX pretreatment has no adverse effect on the 24-hour bonding to ND and AD. Five percent CHX was able to diminish the loss in bonding to AD after 2years of aging in artificial saliva and under simulated IPP.